Vanadium is listed as an inorganic superfund target chemical, known to have toxic health effects, and found at superfund sites. Inhalation is a frequent route of entry into the human body. The ultimate chemical species of vanadium to enter cells relates to its chemical form in environmental particles as well as the fluid media encountered in tissues. The extracellular liquids and their contents as well as intracellular compartments may influence the species of vanadium that ultimately interacts with cellular constituents to produce adverse effects. Two important adverse responses in the lung related to vanadium exposure are the generation of active oxygen metabolites and the induction of pro- inflammatory cytokines. These events occur in pulmonary alveolar macrophages (PAMS) which play a central role in the protection of the lung and the development of pulmonary disease. The specific aims of the studies that we propose are; 1) to define the dissolution patterns and chemical forms of vanadium compounds in the lung, 2) to determine the dose of vanadium compounds in intracellular compartments of PAMs and other lung cells; 3) to determine mechanisms by which these compounds produce massive increases in active oxygen metabolites; 4) to determine mechanisms by which vanadium compounds induce pro-inflammatory cytokines; and 5) to assess these mechanisms of toxicity in human PAMs obtained by bronchoalveolar lavage from workers occupationally exposed to vanadium compounds and non- smoking, non-exposed human volunteers. Assessments of these cells will focus upon the mechanisms defined in our other specific aims so that all our studies will model human exposure at a superfund site. The correlation of our research with that of Project 5 will allow us to directly correlate our mechanistic findings with an in vivo human exposure situation. We will use the Zeiss CEM902 electron microscope's electron energy loss technology for quantification and direct visual correlation of elemental localization and pathologic effects within the cytoplasm of cells. Biochemical, pharmacologic, and molecular approaches will be used to define mechanisms of toxicity/ The novel application of these sophisticated technologies in our proposed studies will offer new insights into intracellular dose- response relationships and mechanisms of toxicity of vanadium compounds.